Group IVB metals include titanium, zirconium and hafnium. One method of producing a purified Group IVB metal, such as metallic titanium, includes the Kroll process, which consists of a reduction stage, purification stage and uniform granulation stage. In the reduction stage, liquid titanium tetrachloride is added to molten magnesium in a reduction vessel whereby the titanium tetrachloride is reduced to porous titanium sponge, with magnesium dichloride as a byproduct. The reaction takes place under an inert atmosphere. Liquid titanium tetrachloride is a feedstock that is produced by carbonation/chlorination of titanium ore. The magnesium dichloride is withdrawn from the vessel to leave titanium sponge with impurities, such as unreacted magnesium and remaining magnesium chloride. Batch production of impure titanium sponge by the Kroll process has a low production rate. For example the reduction process may take several days to produce a few tons of impure titanium sponge. Furthermore after production of the impure titanium sponge, impurities must be removed in the purification stage, which typically involves heating the titanium sponge, either in the reduction vessel, or after scrapping the titanium sponge out of the reduction vessel, to evaporate the remaining magnesium and magnesium chloride. Finally the end product of the Kroll process, namely an intermediate form of metallic titanium comprising a uniform, granulated titanium sponge, is produced typically by crushing and blending. This titanium sponge is used as feesdstock for melting into titanium ingots, typically by an arc or electron beam melting process. The ingots are processed into final products, such as titanium pipes and sheets.
One object of the present invention is to increase the production rate for reducing a feedstock into a sponge form of a Group IVB metal, for example, where the feedstock is titanium tetrachloride and the sponge form is titanium sponge.
Another object of the present invention is to combine the reduction, purification and melting stages for producing a purified Group IVB metal in a single process vessel.